This invention relates in general to power take-offs for selectively driving a driven accessory from a source of rotational power, such as an engine or transmission in a vehicle. More specifically, this invention relates to an improved structure for a such power take-off that includes an axially movable bearing that facilitates the assembly of the power take-off without the use of shims or other axial adjustment devices.
Power take-offs are well known mechanical devices that are commonly used in conjunction with sources of rotational energy, such as vehicular engines and engine-driven transmissions, for selectively providing power to one or more rotatably driven accessories. For example, power take-offs are commonly used in a variety of industrial and agricultural vehicles for operating hydraulic pumps that, in turn, operate hydraulically driven accessories, such as plows, trash compactors, lifting mechanisms, winches, and the like. The power take-off is designed to provide a relatively simple and inexpensive mechanism for supplying rotational power from the source of rotational energy to operate the rotatably driven accessory.
To accomplish this, a typical power take-off includes an input mechanism that is adapted to be connected to the source of rotational energy. The input mechanism is usually embodied as a splined shaft or a toothed gear that is adapted to cooperate with a correspondingly splined or toothed portion contained within the source of rotational energy. Thus, the input mechanism is rotatably driven whenever the source of rotational energy is operated. The power take-off also includes an output mechanism that is adapted to be connected to the rotatably driven accessory. The output mechanism is usually embodied as a splined or keyed shaft that is adapted to cooperate with a correspondingly splined or keyed portion contained within the rotatably driven accessory. In some instances, the input mechanism is directly connected to the output mechanism such that the rotatably driven accessory is always rotatably driven whenever the source of rotational power is operated. In other instances, the input mechanism is connected to the output mechanism through a clutch assembly such that the rotatably driven accessory is selectively rotatably driven only whenever the source of rotational power is operated and the clutch assembly is engaged.
The various components of a typical power take-off, including the input mechanism, the clutch assembly, and the output mechanism described above, are usually supported within a protective housing. To facilitate the assembly of these various components, the housing of the power take-off is often provided in two parts, namely, a main housing portion and a bearing cap. The main housing portion is generally hollow and cylindrical in shape, having a closed end and an opened end. The bearing cap is sized and shaped to be connected to the main housing portion so as to close the opened end and protectively enclose the components of the power take-off contained therein. To assemble the power take-off, the various components of the power take-off described above are initially inserted through the opened end of the main housing portion and assembled therein. Following such assembly, the bearing cap is secured to the main housing portion to close the opened end thereof and provide a sealed enclosure for the various components of the power take-off.
Often, portions of the input mechanism and the output mechanism (such as the ends of the input and output shafts) are supported for rotation on portions of the power take-off housing. For example, the ends of the output shaft of a conventional power take-off are often rotatably supported in a pair of bearings that are respectively disposed within openings formed through the opened end of the main housing portion and through the bearing cap, and many of the components of the power take-off are supported on that output shaft. Although this general structure has been effective, it has been found that manufacturing tolerance variations in the shapes of both the main housing portion and the bearing cap can result in undesirable variations in the axial distance that separates the openings in which the bearings are respectively supported. In some instances, these axial distance variations can result in undesirable axial looseness between the two bearings and the components of the power take-off that are supported on the output shaft. When this occurs, it is known to provide one or more annular shims on the output shaft to take up such axial looseness. In other instances, these axial distance variations can result in undesirable axial compression of the two bearings by the components of the power take-off that are supported on the output shaft. When this occurs, it is known to provide one or more annular shims between the main housing portion and the bearing cap of the housing of the power take-off to relieve such axial compression. However, the use of such shims can add undesirable cost and labor time to the assembly of the power take-off. Thus, it would be desirable to provide an improved structure for a power take-off that obviates the need for such shims.